网络传播动力学模拟方法评述

借助计算机实验模拟方法是预警和控制流行病传播的一个重要研究手段。该文以SIS和SIR两种经典传播模型为例,详细地介绍了利用同步更新方法和异步更新方法模拟流行病的传播过程,并比较了两种模拟方法的时空复杂度、联系及差异性。理清两种不同的计算机模拟方法不仅有助于加深对传播动力学的认识,还有助于提出和发展新的理论框架。

Migraine as a sex-conditioned inherited disorder: evidences from China and the world

Migraine is a complex and heterogeneous disorder. Although several genetic models has been proposed including autosomal-dominant/autosomal recessive, sex-linked, sex-limited, mitochondrial, and multi-gene, none of these models can well-explain the transmission of the disease. We hypothesied that migraine is a sex-conditioned inherited disorder （autosomal dominant in females and autosomal recessive in males）. This hypothesis is supported by the evidence such as the locations of genes associated with familial hemiplegic migraine, possibly ＂typical＂ migraine as well （dominantly on chromosome 19p, lq, and 2q）, male：female ratio of prevalence （1：2-1：4）, the mostly youth-onset, the provocation by the contraceptives, the induction by menstruation, and the self-limitation after menopause. Female sex-hormones appear to be the key contributor to a higher prevalence of migraine in female. Socio-environmental factors may also play an important role.

Epidemiological Investigation of Actinobacillus Pleuropneumoniae in Western Shandong

[ Objective ] The aim of this study was to investigate the epidemic status of porcine pleuropneumonia in western Shandong and establish the PCR method of actinobacillus pleuropneumoniae （APP）. [ Method] The epidemic status of APP in lesion tissues of 186 death pigs and 545 health pigs without clinical symptoms was analyzed by PCR method. [ Result] APP positive rate in 186 samples accounted for 43.0% （80/186）, while that in 545 porcine serums accounted for 9.4% （51/545）. [ Conclusion] This PCR method can be used as one of the important means for APP clinical diagnosis.

Epidemiology of hepatitis C virus infection

Globally, hepatitis C virus (HCV) has infected an estimated 130 million people, most of whom are chronically infected. HCV-infected people serve as a reservoir for transmission to others and are at risk for developing chronic liver disease, cirrhosis, and primary hepatocellular carcinoma (HCC). It has been estimated that HCV accounts for 27% of cirrhosis and 25% of HCC worldwide. HCV infection has likely been endemic in many populations for centuries. However, the wave of increased HCV-related morbidity and mortality that we are now facing is the result of an unprecedented increase in the spread of HCV during the 20th century. Two 20th century events appear to be responsible for this increase; the widespread availability of injectable therapies and the illicit use of injectable drugs.

Clinical phenotype and prevalence of hereditary nonpolyposis colorectal cancer syndrome in Chinese population

AIM: To describe systematically the clinical characteristics and phenotype of HNPCC families and the prevalence of HNPCC in the general population of CRC patients in China. METHODS: HNPCC kindreds and CRC patients were from two sources. One was that we consecutively investigated kindreds and patients by ourselves. And the other was the published Chinese and foreign literature related to Chinese HNPCC syndrome. There were 142 HNPCC families fulfilling AC I and/or AC II including 57 families with detailed data, and 3874 general primary CRC patients in all. All statistical tests were two-sided. RESULTS: In AC I families, the number of Lynch syndrome I and II families were 25 (47.2%) and 28 (52.8%) respectively. There were 215 patients (82.4%) with CRC, 67 patients (25.7%) with extracolonic cancer and 50 patients (19.2%) with multiple primary cancers. In all CRC patients, multiple primary CRC were in 41 patients (19.1%), and the first-CRC was right-sided colorectal cancer in 143 patients (66.5%) and rectal cancer in 44 patients (20.5%). 8.8% and 19.2% of the first cancer were CRC and extracolonic cancers. Among those patients whose first cancer was CRC, 66.8% and 19.9% were right-sided colorectal cancer and rectal cancer, respectively. The similar results were found in AC II families. Normal distribution was only found in the distribution of the age of diagnosis of the first cancer in both AC I families (coefficient of skewness: u = 0.81, 0.20<0.40<P<0.50; coefficient of kurtosis: u = 1.13, 0.20<P<0.40,α=0.20) and AC II families (coefficient of skewness: u=0.63, P>0.5> 0.20; coefficient of kurtosis: u = 0.84, 0.20<0.40<P<0.50, α=0.20), but not found in the distribution of the age of diagnosis of the first CRC. When patients with HNPCC-associated cancer suffered from the first malignant tumor in HNPCC families diagnosed by AC I and AC II, the mean age and median age were 45.1±12.7 years and 44.0 years, 45.2±12.7 years and 44.5 years, respectively. The median age of diagnosis of the first tumor of the patients in the later generation was younger than that in the previous generation. Many extracolonic cancers were found to be associated with HNPCC syndrome. Gastric cancer was the most frequent extracolonic cancer followed by endometrial cancer and hepatocarcinoma. In general population of CRC patients, the prevalence of HNPCC diagnosed by AC I and AC II were 1.3% and 2.2%, respectively. CONCLUSION: The clinical phenotype and prevalence of Chinese HNPCC syndrome are similar to those of Europeans and Americans. Gastric cancer is the most common extracolonic malignant tumor. The age of diagnosis of the first malignant tumor tends to be increasingly younger in patients with HNPCC-related tumors.

Hepatitis G virus

A number of new hepatitis viruses (G, TT, SEN) were discovered late in the past century. We review the data available in the literature and our own findings suggesting that the new hepatitis G virus (HGV), disclosed in the late 1990s, has been rather well studied. Analysis of many studies dealing with HGV mainly suggests the lymphotropicity of this virus. HGV or GBV-C has been ascertained to influence course and prognosis in the HIV-infected patient. Until now, the frequent presence of GBV-C in coinfections, hematological diseases, and biliary pathology gives no grounds to determine it as an "accidental tourist" that is of no significance. The similarity in properties of GBV-C and hepatitis C virus (HCV) offers the possibility of using HGV, and its induced experimental infection, as a model to study hepatitis C and to develop a hepatitis C vaccine.

Epidemiological study: Correlation between diet habits and constipation among elderly in Beijing region

AIM To investigate correlations between diet and prevalence of constipation among elderly people in Beijing.METHODS A total of 2776(≥ 60 years) were selected in Beijing region for investigation. Data regarding constipation and diet habits was collected via hierarchical status, segmentation and random cluster sampling. Investigation included constipation-related demographic indicators and diet habits. Door-to-door questionnaires and surveys included daily staple food intakes, frequency of fish, egg, fruits and vegetables consumption. Constipation was defined according to the China Chronic Constipation Diagnosis and Treatment Guideline(2013), with the following constipation judgment indicators: decreased defecation frequency, dry and hard stool, and difficulty in defecation.RESULTS The prevalence of constipation among elderly people in Beijing region was 13%. There was a positive correlation between prevalence of constipation and age, but negative correlations between prevalence of constipation and staple food, fish and dietary fibres(fruits and vegetables) intakes. These differences were all statistically significant.CONCLUSION The prevalence of elderly constipation in Beijing region is closely related to diet habits, and is significantly decreased by high staple foods intake, fish eating and high dietary fibres(fruits and vegetables) consumption.

Clinical features and epidemiology of spondyloarthritides associated with inflammatory bowel disease

Inflammation of axial and/or peripheral joints is one of the most frequent extra-intestinal manifestations complicating the clinical course and therapeutic approach in inflammatory bowel diseases(IBD).The frequency of these complications seems to be similar for both diseases, Crohn's disease and ulcerative colitis.Arthritis associated with IBD belongs to the category of spondyloarthropathies.Axial involvement ranges from isolated inflammatory back pain to ankylosing spondylitis, whereas peripheral arthritis is noted in pauciarticular and in polyarticular disease.Asymptomatic radiological involvement of the sacroiliac joints is reported to occur in up to 50% of patients.Other musculoskeletal manifestations such as buttock pain, dactylitis, calcaneal enthesitis, and thoracic pain are frequently underdiagnosed and, consequently, are not treated appropriately.Several diagnostic approaches and criteria have been proposed over the past 40 years in an attempt to correctly classify and diagnose such manifestations.The correct recognition of spondylarthropathies needs an integrated multidisciplinary approach in order to identify common therapeutic strategies, especially in the era of the new biologic therapies.

Novel Antiviral Agents Targeting HIV Entry and Transmission

Studies of the mechanism of HIV entry and transmission have identified multiple new targets for drug development. A range of inhibitors have demonstrated potent antiretroviral activity by interfering with CD4-gp120 interaction,coreceptor binding or viral-cell fusion in preclinical and clinical studies. One of these agents,fusion inhibitor enfuvirtide,is already in clinical use. Here we review the progress in the development of specific entry inhibitors as novel therapeutics. The potential of entry inhibitors as topical microbicides to block HIV transmission is also discussed.

Injection drug use and HIV/AIDS transmission in China

After nearly three decades of being virtually drug free, use of heroin and other illicit drugs has re-emerged in China as a major public health problem. One result is that drug abuse, particularly heroin injection, has come to play a predomi- nant role in fueling China’s AIDS epidemic. The first outbreak of HIV among China’s IDUs was reported in the border area of Yunnan province between China and Myanmar where drug trafficking is heavy. Since then drug-related HIV has spread to all 31 provinces, autonomous regions and municipalities. This paper provides an overview to HIV/AIDS transmission through injection drug use in China. It begins with a brief history of the illicit drug trade in China, followed by a discussion of the emergence of drug related AIDS, and a profile of drug users and their sexual partners who have contracted the virus or who are vulnerable to infection. It ends by summarizing three national strategies being used by China to address both drug use and AIDS as major health threats.

Epidemiology and transmission of hepatitis B and C viruses in Kazakhstan

AIM: To investigate the epidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in the two major ethnic groups in Kazakhstan. METHODS: A cross-sectional prospective study of HBV and HCV seroprevalence was performed among individuals born in Kazakhstan with no history of chronic hepatitis or liver disease. RESULTS: There were 290 volunteers (140 Russians and 150 Kazakhs) aged 10 to 64 years, males accounted for 46%. Active HBV infection (HBsAg positive) was present in 3.8%, anti-HBc in 30%. The prevalence was similar in females and males (33% vs 25%) (P = 0.18). The prevalence of anti-HBc increased from 19% in 10-29 years old volunteers to 53% in 50-years and older volunteers. The prevalence of HBV infection was higher in married than in single adults (38% vs 26%, respectively) (P = 0.2) and more common in Kazakhs (35%) than in Russians (24%) (P = 0.07). HCV infection was present in 9 subjects (3.2%), 5 of them also were positive for anti-HBc in the absence of HBsAg. CONCLUSION: The frequency of active HBV infection (3.8%) coupled with a high prevalence of HBV exposure in those > 50 years of age increases with age, which suggests that horizontal transmission likely relates tothe use of contaminated needles. The low prevalence of HCV infection suggests that HBV and HCV are acquired differently in this group of subjects.

Genetic epidemiology of primary sclerosing cholangitis

The aetiology of primary sclerosing cholangitis (PSC) is not known. A more than 80-fold increased risk of PSC among first-degree relatives emphasizes the importance of genetic factors. Genetic associations within the human leukocyte antigen (HLA) complex on chromosome 6p21 were detected in PSC 25 years ago. Subsequent studies have substantiated beyond doubt that one or more genetic variants located within this genetic region are important. The true identities of these variants,however,remain to be identified. Several candidate genes at other chromosomal loci have also been investigated. However,according to strict criteria for what may be denominated a susceptibility gene in complex diseases,no such gene exists for PSC today. This review summarises present knowledge on the genetic susceptibility to PSC,as well as genetic associations with disease progression and clinical subsets of particular interest (inflammatory bowel disease and cholangiocarcinoma).

HIV/AIDS in Asia:The Shape of Epidemics and Their Molecular Epidemiology

The Asia-Pacific region is a home to 60% of the population in the world and to approximately one quarter of people with HIV/AIDS. Close to a million of people has been infected and a half million people died of AIDS annually in Asia,becoming the second largest epicenter of global AIDS epidemic. Molecular epidemiology has been useful tool to track a course of HIV spread. In-depth knowledge from the studies on molecular epidemiology elucidates the dynamics of HIV spread and the interrelationship of epidemics in the different regions in Asia.

Epidemiology of functional gastrointestinal disorders in children and adolescents: A systematic review

To assess the prevalence of functional gastrointestinal disorders (FGIDs) in children and adolescents.METHODSPubMed, EMBASE, and Scopus databases were searched for original articles from inception to September 2016. The literature search was made in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. For inclusion, each study had to report epidemiological data on FGIDs in children between 4 and 18 years old and contain standardized outcome based on Rome II, III or IV criteria. The overall quality of included epidemiological studies was evaluated in accordance with Loney’s proposal for prevalence studies of health literature. Two reviewers assessed each study for data inclusion and extraction. Discrepancies were reconciled through discussion with seniors.RESULTSA total of 659 articles were identified from the databases and 16 through manual search. A total of 43 articles fulfilled the eligibility criteria for full-text reading, with 26 remaining to be included in the final analysis. All studies were written in English and published between 2005 and 2016. Eight (30.8%) articles were performed in North America, five (19.2%) in Latin America, five (19.2%) in Europe, seven (27%) in Asia, and one (3.8%) in Africa. Sample size varied between 114 and 99416 subjects, totaling 132600 individuals. Fourteen (53.9%) studies recruited their target samples from schools, 11 (42.3%) from healthcare settings and the remaining one (3.8%) from online panel community. The overall FGID prevalence rates for student samples ranged from 9.9% to 29% to as high as 87% in clinical samples. Cyclic vomiting, irritable bowel syndrome and functional constipation were the most researched conditions, with a prevalence ranging from 0.2% to 6.2%, 0% to 45.1% and 0.5% to 86.9%, respectively. The qualitative appraisal revealed that most of the studies showed average or below average generalizability.CONCLUSIONThe heterogeneity of the studies on FGIDs must be improved in order to allow comparison. Improvements should include appropriate sampling of representative population, comparable study setting, and consistent data collection.

A shield against a monster:Hepatitis C in hemodialysis patients

Hepatitis C virus(HCV)infection is highly prevalent among patients on hemodialysis(HD).The prevalence of HCV infection in HD patients varies markedly from country to country.Some factors are especially related to these high prevalence rates,such as blood transfusions and length of dialysis time. Nosocomial routes of transmission including the use of contaminated equipment and patient-to-patient exposure is considered more important.Several prophylactic measures have been suggested to avoid infection by HCV in the HD environment.

ReTweeting Analysis and Prediction in Microblogs: An Epidemic Inspired Approach

Microblogs currently play an important role in social communication. Hot topics currently being tweeted can quickly become popular within a very short time as a result of retweeting. Gaining an understanding of the retweeting behavior is desirable for a number of tasks such as topic detection, personalized message recommendation, and fake information monitoring and prevention. Interestingly, the propagation of tweets bears some similarity to the spread of infectious diseases. We present a method to model the tweets' spread behavior in microblogs based on the classic Susceptible-Infectious-Susceptible (SIS) epidemic model that was developed in the medical field for the spread of infectious diseases. On the basis of this model, future retweeting trends can be predicted. Our experiments on data obtained from the Chinese micro-blogging website Sina Weibo show that the proposed model has lower predictive error compared to the four commonly used prediction methods.

Study on the serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) in patients with Helicobacter pylori Infection

Objective: To evaluate the interaction between serum levels of soluble intercellular adhesion molecule 1 (sICAM 1) and Helicobacter pylori (H. pylori) infection in patients with chronic gastritis and peptic ulcer. Methods: The serum levels of sICAM 1 in 205 patients with chronic gastric diseases were detected by ELISA method and the status of H. pylori was determined by histologic examination, RUT, 14 C UBT, and serology. The sera obtained from 18 healthy volunteers served as controls. Results: The serum levels of sICAM 1 were significantly higher in patients with H. pylori positive than those of H. pylori negative (889.43±32.52 ng/ml vs. 747.07±30.45 ng/ml, P <0.05). The serum levels of sICAM 1 in patients with mild, moderate and severe infection of H. pylori were 841.68±72.36 ng/ml, 905.43±37.59 ng/ml and 1012.54±49.34 ng/ml,respectively ( P <0.05). The serum levels of sICAM 1 proved to be significantly correlated with the density of H. pylori colonization in gastric mucosa ( r s =0.316, P < 0.001) . The serum levels of sICAM 1 in patients with chronic gastritis and peptic ulcer were significantly higher than those in healthy controls ( P <0.05). Conclusions: These results indicated that H. pylori infection up regulates the expression of sICAM 1.

Epidemic Spreading Model Based on Social Active Degree in Social Networks

In this paper,an improved Susceptible-Infected-Susceptible(SIS) epidemic spreading model is proposed in order to provide a theoretical method to analyze and predict the spreading of diseases.This model is based on the following ideas:in social networks,the contact probability between nodes is decided by their social distances and their active degrees.The contact probability of two indirectly connected nodes is decided by the shortest path between them.Theoretical analysis and simulation experiment were conducted to evaluate the performance of this improved model.Because the proposed model is independent of the network structure,simulation experiments were done in several kinds of networks,namely the ER network,the random regular network,the WS small world network,and the BA scale-free network,in order to study the influences of certain factors have on the epidemic spreading,such as the social contact active degree,the network structure,the average degree,etc.This improved model provides an idea for studying the spreading rule of computer virus,attitudes,fashion styles and public opinions in social networks.

Acute acalculous cholecystitis in children

Acute acalculous cholecystitis(AAC) is the inflammatory disease of the gallbladder in the absence of gallstones. AAC is estimated to represent at least 50% to 70% of all cases of acute cholecystitis during childhood. Although this pathology was originally described in critically ill or post-surgical patients, most pediatric cases have been observed during several infectious diseases. In addition to cases caused by bacterial and parasitic infections, most pediatric reports after 2000 described children developing AAC during viral illnesses(such as Epstein-Barr virus and hepatitis A virus infections). Moreover, some pediatric cases have been associated with several underlying chronic diseases and, in particular, with immune-mediated disorders. Here, we review the epidemiological aspects of pediatric AAC, and we discuss etiology, pathophysiology and clinical management, according to the cases reported in the medical literature.

Epidemiological Analysis of Syphilis in China From 1985 to 2000

Objectives: To understand trends and epidemiological featuresof syphilis over the recent years in China and provide a scien-tific basis for developing prevention strategies. Methods: From 1985 to 2000, syphilis case-reporting datacollected from all provinces, autonomous regions and munici-palities were analyzed by applying epidemiological methods. Results: (1) Epidemic trends: syphilis incidence has steadilyrisen in China from 1985 to 2000, especially after 1993, when itassumed an exponential growth pattern. 80,406 cases of syphi-lis were reported in the country in 1999, which was almost 40times the number reported in 1993. During the period of1993-1999, the annual average growth of the syphilis incidencerate was 83.55%. Perhaps due to a recent national law en-forcement campaign, the number of reported syphilis casesdropped slightly in 2000. (2) Geographical distribution: Syphi-lis spread from coastal, 'open' cities (especially some cities inFujian province) to inland urban areas, then to rural areas.Regions with a high incidence rate of syphilis in China were theMinjiang, Yangtze, and Zhujiang River Deltas, Beijing andTianjin municipalities, and Northeast China. There was a sig-nificant difference of syphilis incidence rates and growth ratesbetween these areas. A serious epidemic occurred in some ar-eas, with an incidence rate reaching over 200 cases out of100,000. (3) Population distribution: the ratio of male and fe-male cases gradually changed from 1.57:1 in 1993 to 1.02:1 in2000. The rate was the highest in the 20-29 age group and thelowest in 10-14 age group. A great difference existed in preva-lence between different population groups and different areas,and some areas with serious epidemics had high prevalencerates even amoung the general population. (4) Clinical stage ofsyphilis: Primary and secondary syphilis cases have beendominating with a percentage of 90% of all syphilis cases. Pri-mary syphilis was the most common in males and secondarysyphilis in females. Secondary and latent syphilis cases in fe-males were more than in males. (5) The congenital syphilisincidence has increased dramatically. Two cases were reportedin 1991 and 468 cases in 2000. Conclusion: The syphilis epidemic in China became muchmore severe between 1985 and 2000, and such increasingtrends deserve our serious attention.